pretty standard I think. Last time we rented in the USA on top of the rental charge was $15/day loss damage waiver (to reduce the liability from the value of the bike down to $1000) and $15 for the $300,000 public liability insurance.

The principle...yes.
The amounts?...sobering!
USD60 is close enough to A$100/day....just for extra-insurance!

There are actually various US/UK insurance mobs that offer those covers for a lot less.
(worth it for anything longer than about a week's rental).
We had one of those when renting cars in US-territory Puerto Rico/ Caribbean